In many systems in which processors are utilized, short power failures can hamper the operation of the systems. A power failure is a state wherein at least one supply voltage drops to a level below which continued operation of the system will become unreliable or impossible.
The problem is more severe in mobile systems, or in systems of compact size, which has relatively small energy reservoir, which can store a limited amount of electromagnetic energy, to be supplied during a power failure. These reservoirs can supply energy for a relatively short period.
If a power failure occurs, the status of the processors in the mobile radio is not saved, causing vital information to be erased. A power failure can cause a mobile radio, which was in a receiving mode, to shut down, because the data relating to the receiving mode was erased as a result of the power failure.
Power failures, and particularly short power failures, can occur for many reasons. A short power failure can occur when the mobile radio is hit and the mobile radio battery is momentarily disconnected from the rest of the electrical circuitry of the mobile radio.
In cellular communication, radios and radio base stations (i.e.--"base") exchange data and control signals. The radio and base need to be time synchronized in order to transmit and receive signals to be properly interpreted by the radio and the base. In both radio and base there are timing units for timing events executed within the radio and the base. Short power failures within radio can cause the timing unit within radio to be reset, or be halted, resulting in a unknown gap between the timing unit of the radio and the base.
Accordingly, there is a need for an apparatus and method for maintaining the status of processors, during power failures. Accordingly there is a need for an apparatus and method for maintaining the synchronization between radio and base, regardless of any short power failures.
As used therein, the word "processor" is intended to refer to any kind of signal processor, as for example and not limited to, digital signal processors, processors and microcontrollers.
As used therein, the word "radio" or "mobile radio" is intended to refer to any kind of electrical apparatus which their components store a limited amount of energy to continue to deliver power during the whole power failure period, wherein the electrical apparatus can have a plurality of processor.